1. Field of the Invention.
The present invention relates to the disposal of nuclear or toxic waste materials and more particularly to the method for the permanent disposal of these materials by placing them in the descending tectonic plate at the edge of the subduction zone.
2. Description of the Prior Art.
The disposal of radioactive wastes from nuclear reactors and other activities of atomic energy research, is a problem facing world socity. This problem arises from the long half-life of the radioactive waste products and the toxicity of the chemical compounds in which the radioactive material is found. The magnitude of the problem can be seen from the realization that about 2.23 m.sup.3 of solid waste are produced by a conventional 1,000 MW reactor each year and five hundred such reactors would produce approximately 1,115 m.sup.3 of solid waste each year. Plutonium 239, which is part of the solid waste of these reactors, has a half-life of nearly 25,000 years. Ten half-lives are required to reduce the radioactivity by a factor of 1,000 which is generally considered the required safety level. Thus it is estimated the buried Plutonium 239 wastes must be kept out of the biosphere or environment for 250,000 years or longer. The requirement is to dispose of this material in a manner and location where it is impossible for the waste to find its way back into the environment for at least 250,000 years and preferably longer.
The present accumulation of processed nuclear waste is stored in large vats of water, while a cooling process takes place. Sites such as salt domes, desert storage areas and ocean sediment deposits are being surveyed for use as permanent disposal areas. The major difficulty with these sites is that natural upheavals could cause the release of waste from salt domes or sediment deposits. In addition, any land storage is subject to undesirable future human tampering. Moreover, these wastes are thermally hot and may melt the salt in the salt domes, unless expensive cooling procedures are operative, and thereby escape their environment. Another major concern in waste disposal is that land located waste may seep back into or otherwise contaminate our water supplies.
Early in 1960, geophysicists realized that the crust of the earth was formed of large solid basaltic plates moving relative to each other. These large basaltic plates are formed at ocean ridges and return to the center of the earth at places known as "subduction" zones. The plates re-enter the earth at about 6 cm per year.
In accordance with the method and apparatus of the present invention the above described problems are overcome by placing the waste material in bore holes made in the basement rock of an oceanic plate at the edge of its subduction zone. This allows the crustal movement of the basement rock to carry the waste to the interior of the earth. About 58 million years are required before this waste material might again find its way to the earth's surface. Sufficient distances of subduction oceanic plate exists west of Washington and Oregon and south of the Aleutian chain to accommodate the waste output of the world for many centuries.